uniform mat4 vMatrix;
varying vec4 vColor;
attribute vec4 vPosition;

void main(){
    gl_Position=vMatrix*vPosition;
    if(vPosition.z!=0.0){
        vColor=vec4(0.0,0.0,0.0,1.0);   //顶点颜色，会自动和连接点颜色形成渐变
    }else{
        vColor=vec4(0.9,0.2,0.9,1.0);   //扇形边缘点颜色
    }
}